Composite structures are typically formed by laying up multiple plies on a tool. Each ply may include a reinforcing material, such as carbon fiber, and may be pre-impregnated with a resin. Multiple plies are applied, one upon another, often in multiple directions, to form a layup. Excess composite material often must be cut from the layup, either before or after the layup is cured.
The cutting of a composite layup, particularly an uncured composite layup, can be difficult, particularly when a clean edge is desired. Therefore, ultrasonic cutting machines are typically employed when cutting composite layups. The use of ultrasonic energy (as compared to a purely mechanical cut) reduces the likelihood that the cutting blade will adhere to the layup and drag one or more plies out of position, particularly when the layup is relatively thick.
Over time, the cutting blade on an ultrasonic cutting machine can accumulate fiber and resin. Such a build-up of debris may impede cutting, and may cause reinforcing material to fray and/or pull from the plies, thereby compromising the quality of the resulting cured composite structure. Frequent replacement of ultrasonic cutting blades is one solution, but is expensive and time consuming. Frequent cleaning of ultrasonic cutting blades is another solution—it creates a higher quality cut and may extend cutting blade life.
Manual cleaning of cutting blades, while effective, presents safety issues and can be time consuming. Therefore, automated cutting blade cleaning has been explored. In one known example, ultrasonic cutting blades have been dipped into a basin of solvent, energized with ultrasonic energy while still submerged in the solvent, and then dried in air by again energizing the cutting blade. However, energizing ultrasonic cutting blades in a solvent presents various issues depending on the type of solvent used. If the solvent is an organic solvent, energizing an ultrasonic cutting blade in the solvent presents a potential fire hazard. Using water as a solvent eliminates the potential fire hazard, but water is often prohibited in composite fabrication facilities, and water is not a particularly effective solvent for composite resins.
Accordingly, those skilled in the art continue with research and development efforts in the field of ultrasonic cutting machine blade cleaning.